This invention relates to the handling of sheets of material of the type which respond to magnetic forces and is more particularly concerned with improvements in apparatus which includes magnetic roll or roller means for conveying such sheets in a predetermined path.
In sheet piling equipment, and in other apparatus for handling sheets or plates of magnetizable materials, various arrangements have been developed for conveying the sheets so as to enable them to be dropped onto a pile in a piling operation, or to deliver them to another desired location. One form of conveying arrangements which has been used with a high degree of success, particularly, in sheet fabricating mills and similar locations, comprises endless traveling belts with associated fixed magnet units disposed so as to provide a flux path for holding the sheets against the belt surface and causing the material to travel with the belts. Arrangements of this type are disclosed in U.S. Pat. Nos. 3,199,654, dated Aug. 10, 1965, and 3,229,805, dated Jan. 18, 1966. In most situations, the belt type conveyor arrangement is found to be most efficient and economical in handling the sheets with minimum or no damage to the sheet surfaces which engage the belts. In some situations, a magnetic roll or roller arrangement is preferred for various reasons. However, the roller arrangements heretofore provided have certain disadvantages. The roller contact with the sheet surface is along a relatively narrow rigid line so that there is no flexibility axially of the roller and the flux path is held quite narrow with consequent loss in effectiveness, or a need for greater strength magnets. In many arrangements, particularly, when handling heavy metal plates, big heavy rolls or rollers and high magnetic power is required which greatly increases the cost of operation.
A general object of the present invention is to provide equipment for handling magnetizable sheet material which includes an improved conveyor arrangement having incorporated therein sheet supporting and conveying rollers with associated magnet structures which greatly increase the efficiency of the rollers and render them more versatile in use.
A more specific object of the invention is to provide improved apparatus for handling sheets of magnetizable material which includes an overhead magnetic conveyor means having one or more magnetic roll units adapted to be supported in a flexible chain like arrangement for engaging in supporting and conveying relation sheet material which may have an irregular top surface resulting in a reduction in the area of contact available for engagement with the normally rigid roll surface.
Another object of the invention is to provide in magnetizable metal sheet or plate handling apparatus an improved overhead conveyor comprising one or more roll or roller units having incorporated therein an electromagnet in the form of a coil and a core which constitutes a fixed shaft with extended ends on which wheel-like rollers are rotatably mounted in axially spaced relation so that the periphery thereof travels in a path for engagement with the top surface of the sheet material and the core structure having axially spaced extension members positioned adjacent the sheet contacting rollers which present a downwardly facing surface spaced a small distance from the path of the sheet and extending fore and aft of each of the associated rollers so as to provide a flux path which is of substantially greater width than the corresponding dimension of roll surface in contact with the sheet.
To this end the invention as claimed herein is embodied in sheet handling apparatus in which means is provided for advancing in a predetermined path sheet material of a character which is responsive to magnetic attraction, which apparatus includes one or more rotatably mounted sheet engaging roll members and associated means providing a path for magnetic flux which spreads the flux over an area substantially greater than the area of the roll surface in contact with the material being conveyed.
The foregoing and other objects and advantages of the invention will be best understood when reference is made to the accompanying description of the preferred form of the invention which is set forth herein, by way of example, and shown in the drawings wherein like reference numerals indicate corresponding parts throughout.